Magnetic properties of superconducting permanent magnets of YBa₂Cu₃O_x

DC magnetic properties were measured in the melt processed YBa₂Cu₃O_x after field-cooling using a SQUID magnetometer. The magnetic properties estimated from the demagnetizing curves showed that the samples worked as strong bulk permanent magnets. This is attributed to the large pinning forces obtained in the bulk superconductors. The dependence of the magnet properties on the applied fields in field-cooling indicates that the properties can be continuously changed using the field-cooling technique. The magnet properties of the Melt-Powder-Melt-Growth processed YBa₂Cu₃O_x with 1.5mm thickness obtained at 5 K after field-cooling in 10 kOe (H//c) are as follows: the residual flux density, B_r is 9.6kG, the coercive force, _bH_c is 33kOe and the maximum energy product, (BH)_max is 110MGOe.